In referring to the recent results of the AMS experiment in the ISS: http://physics.aps.org/articles/v6/40 I'm still left wanting of understanding why the presence of an excess of positrons infiltrating the device isometrically indicates a presence of dark matter and tells me something about it. What I'm getting is that this positron excess is supposed to be reflective of annihilation events in the dark matter. From the article: But if we don't know what dark matter is, how can we say that annihilation events would produce excess positrons, or positrons at all? I don't know if I'm feeling my 2 billions dollars working for me here. Can someone enlighten me?